This invention relates to apparatus and a method for forming heated glass sheets while providing alignment between lower and upper molds used in the forming.
Glass sheets are conventionally formed by heating within a furnace and then forming within a heated chamber prior to delivery for cooling. Such cooling can be slow cooling to provide annealing or faster cooling that provides heat strengthening or tempering. In connection with heating of the glass sheets, see U.S. Pat. No. 3,806,312 McMaster et al. U.S. Pat. No. 3,947,242 McMaster et al.; U.S. Pat. No. 3,994,711 McMaster; U.S. Pat. No. 4,404,011 McMaster; and U.S. Pat. No. 4,512,460 McMaster. In connection with glass sheet forming, see U.S. Pat. Nos. U.S. Pat. No. 4,282,026 McMaster et al.; U.S. Pat. No. 4,437,871 McMaster et al.; U.S. Pat. No. 4,575,390 McMaster; U.S. Pat. No. 4,661,141 Nitschke et al.; U.S. Pat. No. 5,004,491 McMaster et al.; and U.S. Pat. No. 5,472,470 Kormanyos et al. In connection with the cooling, see U.S. Pat. Nos. U.S. Pat. No. 3,936,291 McMaster; U.S. Pat. No. 4,470,838 McMaster et al.; U.S. Pat. No. 4,525,193 McMaster et al.; U.S. Pat. No. 4,946,491 Barr; and U.S. Pat. No. 5,385,786 Shetterly et al.
During the forming process, the heated glass sheets can be supported by a vacuum generated at a downwardly facing mold whose initial support of the glass sheet upon being received from a heating conveyor can be assisted by an upwardly directed heated gas flow that can be provided by gas jet pumps, such as disclosed by U.S. Pat. No. 4,204,854 McMaster et al. and U.S. Pat. No. 4,222,763 McMaster.
For effective high yield glass sheet forming, it is important for cooperable molds to be properly positioned upon mounting and aligned with each other during each cycle of operation therebetween, which is made more difficult due to the heated environment in which the glass sheet forming takes place. See, U.S. Pat. No. 4,781,745 Mumford; U.S. Pat. No. 5,158,592 Buckingham; U.S. Pat. No. 5,092,916 McMaster; and U.S. Pat. No. 5,230,728 McMaster. The heated environment also makes it more difficult to change molds between different production runs that cannot utilize the same molds. See U.S. Pat. No. 5,137,561 Schnabel, Jr. which discloses changing a cloth ring on a glass sheet heating furnace.
After forming, heat strengthening or tempering can be performed by rapid cooling at a quench section between lower and upper quench modules thereof and may have provision for transferring the glass sheet during such cooling by blowing a greater amount of gas upwardly so as to permit the associated quench ring that carries the glass sheet to move back to the heated forming station in preparation for the next cycle. See U.S. Pat. No. 4,361,432 McMaster et al.
All of the above cited patents are hereby incorporated by reference.
One object of the present invention is to provide improved apparatus for forming heated glass sheets.
In carrying out the above object, the apparatus for forming heated glass sheets in accordance with the invention includes a housing having a heated chamber. An upper mold support assembly of the apparatus supports an upper mold within the heated chamber for cyclical vertical movement between upper and lower positions. A lower mold shuttle of the apparatus supports a lower mold for cyclical movement between an idle position horizontally spaced from the upper mold and a use position below the upper mold. The apparatus also includes a lower mold support assembly to which the lower mold is cyclically transferred from the lower mold shuttle in the use position to provide support thereof while permitting horizontal alignment of the lower mold with the upper mold as necessary upon each cycle of downward movement of the upper mold for cooperation of the molds to form a heated glass sheet between the molds.
In its preferred construction, the apparatus includes vertically movable rollers having an upper position that supports the lower mold shuttle during the cyclical movement of the lower mold between the idle and use positions and having a lower position at which the lower mold shuttle is moved downwardly with the lower mold in the use position to provide cyclical transfer of the lower mold to the lower mold support assembly. Horizontal positioners cooperate with the rollers to support and guide the lower mold shuttle during the cyclical movement of the lower mold between the idle and use positions. The apparatus also includes mounts supported externally of the heated chamber for vertical movement with each mount supporting one of the rollers and an associated pair of the horizontal positioners.
In the preferred construction, the lower mold support assembly includes four lower supports that support the lower mold in the use position below the upper mold. Each lower support in one embodiment includes a liquid cooled ball and in another embodiment includes a liquid cooled pad that is preferably made from a carbon material.
A support member mounts the lower mold supports of the lower mold support assembly and also mounts a support and stop member that positions an array of gas jet pumps that operate to assist in initially supporting a heated glass sheet on the upper mold.
In the preferred construction, the lower mold shuttle also includes a lock that secures the lower mold against movement on the lower mold shuttle along its direction of travel during the movement between the idle and use positions.
The lower mold shuttle of the apparatus preferably has a tubular construction through which a liquid coolant flows to provide cooling. In addition, the tubular construction of the lower mold shuttle includes an outer insulator.
The apparatus for forming glass sheets also preferably includes a quench station having lower and upper quench modules for supplying a quench gas. A quench shuttle supports and cyclically moves a quench ring between S transfer and quench positions. In the transfer position, the quench ring is located below the upper mold in the heated chamber and the quench ring is movable horizontally on the quench shuttle as necessary into alignment with the upper mold upon downward movement of the upper mold to deposit a formed glass sheet supported thereby onto the quench ring. In the quench position, the quench ring is located between the lower and upper quench modules to provide quenching of the formed glass sheet on the quench ring. The apparatus also includes a lock for preventing horizontal movement of the quench ring on the quench shuttle during movement between the transfer and quench positions. In addition, the quench station includes a railway having a pair of spaced rails. The quench shuttle includes a pair of spaced shuttle members having supported ends that are respectively supported by the pair of spaced rails for the movement of the quench shuttle, and the spaced shuttle members also include a pair of cantilevered ends that support the quench ring in a spaced and otherwise unconnected relationship.
Alignment guides on the lower and upper molds cooperate to move the lower mold horizontally on the lower mold support assembly as necessary into alignment with the upper mold upon each cycle of downward movement of the upper mold to the lower position to provide the glass sheet forming.
Another object of the invention is to provide an improved method for forming a glass sheet.
In carrying out the above object., the method for forming a glass sheet is provided by heating the glass sheet during conveyance thereof on a horizontally extending conveyor. An upper mold is moved downwardly to receive the heated glass sheet from the conveyor and is then moved upwardly with the glass sheet supported thereby in preparation for the forming. A lower mold is then moved horizontally on a lower mold shuttle from an idle position horizontally spaced from the upper mold to a use position below the upper mold with the glass sheet supported thereby. The lower mold is then transferred in the use position from the lower mold shuttle to a lower mold support assembly, and thereafter the upper mold is moved downwardly toward the lower mold and the lower mold is moved horizontally on the lower mold support assembly as necessary into alignment with the upper mold whereupon the continued movement of the molds toward each other forms the glass sheet between the molds. Finally, the upper mold is moved upwardly and the lower mold is transferred from the lower mold support assembly back to the lower mold shuttle for horizontal movement thereon from below the upper mold back to the idle position to permit delivery of the formed glass sheet from the upper mold for cooling.
In the preferred practice of the method, the lower mold shuttle is supported by rollers during the horizontal movement on the lower mold between the idle and use positions, and the rollers are moved vertically to transfer the lower mold between the lower mold shuttle and the lower mold support assembly. The lower mold is locked on the lower mold shuttle to prevent movement with respect thereto along the direction of travel during the movement thereof between the idle and use positions.
In the preferred practice of the method, the formed glass sheet is deposited from the upper mold onto a quench ring for delivery to a quench station for quenching. The quench ring is moved on a quench shuttle and is locked with respect thereto during movement between the upper mold and the quench station but is unlocked at the upper mold to permit movement with respect to the quench shuttle into alignment with the upper mold.